In this April 3, 2008 file photo, Gary Michael Hilton appears at the Lamar County Superior Courthouse in Barnesville, Ga.

ASHEVILLE, N.C. -- A drifter convicted of gruesome hiker slayings in two states pleaded not guilty Monday to charges that he killed two more people on a national forest trail in North Carolina.

Prosecutors say Gary Michael Hilton camped out waiting for victims before he encountered Irene and John Bryant and killed them in October 2007. Hilton made his initial appearance in U.S. District Court in Asheville on charges of kidnapping, robbery and murder in the deaths of the retired couple. The case is being handled in federal court because the Bryants were killed in a national forest.

Hilton pleaded guilty to the killing of Meredith Emerson, of Buford, in 2007.

Hilton, 65, wore a white Buncombe County jail jumpsuit and said nothing during his brief appearance. One of his lawyers entered his plea for him. A trial date of Sept. 6 has been set.

Family and friends say the Bryants followed their passion for hiking around the world, tramping across Europe, New Zealand and along the Appalachian Trail. They were killed not far from their home in Hendersonville.

"What really ticks you off about this whole thing is, they used to backpack and hike all over the world," said Charlie Major, a longtime friend of the couple who served for decades alongside John Bryant in local government in the upstate New York town of Skaneateles. "They did the whole Appalachian Trail, they hiked from one coast of Scotland to the other. And then to go hiking and get killed almost in their own backyard is so awful it's unbelievable."

Prosecutors could seek the death penalty on top of sentences the 65-year-old Hilton has already received: life in prison for the murder of Meredith Emerson in Georgia and death row for the murder of Cheryl Dunlap in Florida. The bodies of both women were beheaded.

The bodies of the four victims were found over a span of several months starting in late 2007, and Hilton pleaded guilty in the Georgia case weeks after his arrest there in Jan. 2008. He was convicted in the Florida case earlier this year, and his indictment in the North Carolina case came last month.

With Hilton's court appearance looming, family and friends were focusing on memories of the Bryants' rich lives.

"My father loved practical jokes, but nothing mean-spirited," said Holly Bryant, the couple's daughter, who now lives in Florida. "My mom was a bit more serious, I guess, but it obviously worked because they were married forever."

The couple met on a blind date in Montana when he was working as an engineer there after serving in the Navy during World War II. She was a veterinarian. They were married on July 9, 1949 and stayed together for 58 years, raising four children, moving from Montana to New York to North Carolina, and logging thousands of miles hiking the scenic places of the world. John Bryant became a lawyer and practiced in New York.

"My parents traveled extensively and all over the world, they raised a family, they did what they loved," Holly Bryant said. "They enjoyed their lives to the fullest extent."